Fabry–Perot cavity cascaded sagnac loops for temperature and strain measurements

Abstract. The fabrication process and temperature and strain characterizations of an all-fiber sensor are presented. The sensing structure based on a Fabry–Perot cavity (FPC) and sagnac loops was proposed and experimentally demonstrated for measurements of temperature and strain. The FPC consists of a micropiece of chemical etched multimode fiber end face, welded with another single mode fiber. Then, the sagnac loops composed of polarization maintaining fiber was connected to the FPC. The sensor was fabricated and tested for temperature and strain. Experimental results show that sensitivity of temperature and strain is 0.71  ±  0.03  nm  /    °  C and 1.30  ±  0.01  pm  /  μϵ, respectively; the linearity are 0.9970 and 0.9996, respectively.